What is Disease X? Scientists who discovered Ebola warns against potentially fatal viruses

The scientists who helped discover the Ebola virus in 1976 has warned against an unknown number of new and potentially fatal viruses faced by humanity among which is 'Disease X'. "X" stands for unexpected. As of now, ​​Disease X remains hypothetical, an outbreak that scientists and public health experts fear could lead to serious disease around the world if and when it occurs.

source https://timesofindia.indiatimes.com/india/what-is-disease-x-scientists-who-discovered-ebola-warns-against-potentially-fatal-viruses/articleshow/80107576.cms